As a result of the passage of the Patient Protection and Affordable Care Act (ACA), 52 million Americans without health insurance became eligible for insurance through an exchange system that allows them to choose from multiple health insurance plans. Uninsured individuals are disproportionately low-income, and are more likely to suffer from untreated or poorly managed chronic health conditions. A goal of the ACA is to improve access for the uninsured, lower their out-of-pocket costs, and improve health through better prevention and management of chronic conditions. These goals will only be achieved if individuals understand how to select and use health insurance to meet their financial and health needs. However, making an informed health plan choice is challenging for individuals with little prior experience with this task. Without understanding plan information, individuals are unlikely to make an informed choice that meets both their financial and health needs. This could substantially impact their ability to pay for care to manage and improve their health. Our past research was one of the first to examine currently uninsured individuals' understanding of health insurance and factors important to their insurance decision making. Using information from our study of uninsured individuals, incorporating feedback from key policy stakeholders, and building on best practices in communication science, health literacy, and decision science, we developed strategies to improve decision making about health insurance plans. Our current proposal aims to update these strategies through additional stakeholder input and our past research findings about most successful decision support approaches. We will program a decision support tool online so we can tailor information to users' needs and preferences. Next, we will test the efficacy of our updated decision support tool in a randomized experiment. Finally, we will collect stakeholders' feedback on likelihood of adoption and implementation of the tool. We will use the information developed in this proposal to inform health reform implementation at the state and federal levels, as rules and regulations are written and health insurance exchanges are updated. A future dissemination and implementation study will also compare strategies for delivering this tool to the public.